From 8ca3f7a7b61393804c46f170743c3b839df13977 Mon Sep 17 00:00:00 2001 From: Ido Schimmel Date: Mon, 22 Apr 2024 17:25:59 +0200 Subject: [PATCH] mlxsw: spectrum_acl_tcam: Fix memory leak during rehash The rehash delayed work migrates filters from one region to another. This is done by iterating over all chunks (all the filters with the same priority) in the region and in each chunk iterating over all the filters. If the migration fails, the code tries to migrate the filters back to the old region. However, the rollback itself can also fail in which case another migration will be erroneously performed. Besides the fact that this ping pong is not a very good idea, it also creates a problem. Each virtual chunk references two chunks: The currently used one ('vchunk->chunk') and a backup ('vchunk->chunk2'). During migration the first holds the chunk we want to migrate filters to and the second holds the chunk we are migrating filters from. The code currently assumes - but does not verify - that the backup chunk does not exist (NULL) if the currently used chunk does not reference the target region. This assumption breaks when we are trying to rollback a rollback, resulting in the backup chunk being overwritten and leaked [1]. Fix by not rolling back a failed rollback and add a warning to avoid future cases. [1] WARNING: CPU: 5 PID: 1063 at lib/parman.c:291 parman_destroy+0x17/0x20 Modules linked in: CPU: 5 PID: 1063 Comm: kworker/5:11 Tainted: G W 6.9.0-rc2-custom-00784-gc6a05c468a0b #14 Hardware name: Mellanox Technologies Ltd. MSN3700/VMOD0005, BIOS 5.11 01/06/2019 Workqueue: mlxsw_core mlxsw_sp_acl_tcam_vregion_rehash_work RIP: 0010:parman_destroy+0x17/0x20 [...] Call Trace: mlxsw_sp_acl_atcam_region_fini+0x19/0x60 mlxsw_sp_acl_tcam_region_destroy+0x49/0xf0 mlxsw_sp_acl_tcam_vregion_rehash_work+0x1f1/0x470 process_one_work+0x151/0x370 worker_thread+0x2cb/0x3e0 kthread+0xd0/0x100 ret_from_fork+0x34/0x50 ret_from_fork_asm+0x1a/0x30 Fixes: 843500518509 ("mlxsw: spectrum_acl: Do rollback as another call to mlxsw_sp_acl_tcam_vchunk_migrate_all()") Signed-off-by: Ido Schimmel Tested-by: Alexander Zubkov Reviewed-by: Petr Machata Signed-off-by: Petr Machata Reviewed-by: Simon Horman Link: https://lore.kernel.org/r/d5edd4f4503934186ae5cfe268503b16345b4e0f.1713797103.git.petrm@nvidia.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.c index 568ae7092fe0e..0902eb7651e14 100644 --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.c +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.c @@ -1200,6 +1200,8 @@ mlxsw_sp_acl_tcam_vchunk_migrate_start(struct mlxsw_sp *mlxsw_sp, { struct mlxsw_sp_acl_tcam_chunk *new_chunk; + WARN_ON(vchunk->chunk2); + new_chunk = mlxsw_sp_acl_tcam_chunk_create(mlxsw_sp, vchunk, region); if (IS_ERR(new_chunk)) return PTR_ERR(new_chunk); @@ -1334,6 +1336,8 @@ mlxsw_sp_acl_tcam_vregion_migrate(struct mlxsw_sp *mlxsw_sp, err = mlxsw_sp_acl_tcam_vchunk_migrate_all(mlxsw_sp, vregion, ctx, credits); if (err) { + if (ctx->this_is_rollback) + return err; /* In case migration was not successful, we need to swap * so the original region pointer is assigned again * to vregion->region.